Method and apparatus for operations with a contact mass



May .18, 1948- 4 11.1 SIMPSON IETHOD mm nrrm'rus FOR ormumons 'wnn A CONTACT mss Original Filed larch 3, 1944 2 smug-sheet 1 INVENTOR THOMHS P. JIM/ 50 May'1 8, 1948. T. P. SIMPSON 2,441,724

METHOD APPARATUS FOR OPERATIONS WITH A CONTACT MASS Original Filed March 5, 1944 2 Sheets-Sheet 2 INVENTORA 77/0/1119: .1? SIMPSON Patented May 18, 1948 UNITED STATES PATENT OFFICE METHODYAND APPARATUS FORoPERA 'rrons WITH A CONTACT MASS Thomas P. Simpson, Woodbury, N. J., assignor to Socony-Vacuum Oil Company, Incorporated, a corporation of New York a Original application March 3, '1944, Serial No. 524,925. Divided and this application April 13, 1945, Serial No. 588,173 7 4 Claims. (Cl. 23-1) of processes of this kind is the cracking conver-' sion of hydrocarbons, it being Well known that hydrocarbons of a gas oil nature boiling between about: 500 F. and 750 F; may be cracked to gasoline and other products by passing them at a reaction temperature and pressure such as, for example, temperatures of the order of 750 F and higher and pressures somewhat above atmosphericin contact with a solid adsorptive catalytic contact mass. Usually such contact masses partake of the nature of fullers earth, or other natural or treated clays and/or various synthetic associations of alumina, silica and alumina and silica, any of which may have other constituents added for a purpose in connection with the process such as certain metallic oxides.

medium such as'a combustion supporting gas,

acting to burn off contaminant materials deposited upon the contact mass during reaction. Generally hoppers are provided above each of said zones from which hoppers the contact material gravitates to the said zones through suitable conflned passages and conveyors such as bucket elevators are provided to convey the con-' tact'material from the drain from one zone to the hopper above the other. 7 i

This invention has specifically to do with a method and apparatus'iorithe transferof contact material from the hoppers to the respective zones therebelow; It is usuallynecessary to operate one or both of said zones above-atmospherie pressure and it is generally economical and practically desirable to operate the conveyors and surge hoppers at a pressure below that in the zones such as atmospheric. It has been found that if the confined passage or pipe connected between the hopper and conversion vessel is of suificient vertical length and that if the convertor is operated so as to cause throttling of the flow of contact material from the lower'end of said pipe, the contact material will gravitate down through said pipe and into the convertor against the higher fluid pressure in said convertor.

Such a system is disclosed and covered by the patent to Simpson et al., No. 2,410,309, dated October 31, 1946, in which the present applicant is one of the patentees.

Due to the positive pressure differential between the convertor and the hopper, vapor reactants'or more generally an inert seal vapor generally used in the upper section of the convertor-willpass upwards through the column of downwardly flowin contact material and out from the top of the hopper. This vapor flow has a retarding action on the downward motion of the contact material, the retarding force being greater for particles ofsmaller size and/or lower density. The rate'oi upward vapor flow and the retarding action thereof on the downward iiow;

of contact material in the pipe between the convertor and the hopper increases as the vertical length of said pipe approaches the minimum reableto limit the vertical length of said pipe as near as practical to the minimum required for contact material flow. Also since for the same pressure diiferential between the convertor and hopper therate of vapor flow through the contact material column therebetween will increase with'increase in averageparticle size and since for the same 'vapor'flow rate the retarding effect due thereto varies for difierent size contact material particles, it is desirable to limit the range of particle size of the contact material within as narrow. limits as are practical and to provide sufiicient vertical pipe length between the convertor and hopper to insure downward flow of the smaller particles present in the contact material mass.

material made up of particles ranging from 8 As anexample of a typical practical range of contact material particle size, a

only a little greater than that in th convertor,

the how of contact material through the feed pipe tirelystop and could not generally be recstablish'ed Without release of the convertor pressure.

.1 to the convertor would suddenly substantially en This not only necessitates diverting the reactant vapors from the convertor thereby resulting in the loss of operating time but also seriouslyupsets the operating conditions of the entire cyclic system and of the product fractionating system thereby causing a further loss in operating time.

After extensive investigations it was finally discovered that these unpredictable contact material flow interruptions were caused by gradual accumulations of undersized contact material in the upper section 'of the feed leg, Due to the normal gradual attrition of the contact material particles in the course of flow through a continuous cyclic system such as hereinbefore described, small quantities of fines or undersized material of much smaller diameter than the. average diameter of the normal sized contact material accumulate in the contact material mass and are delivered into the hopper above the feed leg along with the normal size contact material. Up to a certain-maximum percentage of this undersized material'is swept down th-rough thefeed pipe into the converter by the larger particles. V If more than this percentage of undersized material is present in the contact material supply to the convertor feed pipe, the excessis prevented by the upward flowing inert vapor in the feed pipe frorn passi ng down therethrough. In fact, some very small particles which have been sweptdown v a short distanc e into the feed pipe may actually 1 be forced upwards by the vapor fiCW.; Thus the excess undersized ,material gradually accumulates in the upper partof the feed pipeand especially at the top thereof. When the accumu:

lation'at the top of the pipe becomes sufficient the very fine size material and is sufiicient tostop the downward flow of said fine size material and the flow of substantially all the contact material thereab'ove, thereby stoppingthe flow of contact material to the convertor.

A major object of this invention is the provision of a systemfor continuous, uninterrupted introduction of particle form contact mass materialto azone operating under pressure for contactwith a gaseous material therein. 7

A specific object of this invention is the provi sion in a continuous cyclic process of the type hereinbefo're described of a means forDIeventionyof interruptions, due to accumulation of un-,

dersizedcontact material particles, of gravita tional flow of particle form contact mass material in feed pipes to conversion vessels operatling under fluid pressures substantially above those at the inlet to said feed pipes.

These a d. o h r objects. W111 bec me apparent.

'4 in the following description of this invention. Inasmuch as the system of this invention will apply equally well to contact material feed pipes supplying regenerators, convertors or other vessels operating under gaseous ,pressures above those at the supply end of saidfeed pipes, the term convertor will hereinafter be used in the description and claiming of this invention in a sense suiiiciently broad to cover any of these application'sl' In order to better understand this invention reference should now be made to the drawings attached hereto, vIn these drawings, Figure 1 is an elevational view,.partially in section, showing one form of the invention. Figure 2 is an elevational view, partially in section, showing a preferred l method for.'removing undersized contact material from the upper end of the convertor feed pipe. 1 Figure 3 shows an equivalent method and apparatus for accomplishing the same purpose. Figure 4 is an elevational view, partially in section, showing: another preferred apparatus and method for preventing accumulation of undersized contact material in the convertor feed pipe. Figure 5 is a sectional view taken at line 5- -5 in Figure 4.

Turning now to Figure l, we find-aH-hopper 2!) to the top of which is connected contact mate rial inlet pipe 2i, and near the toner which is I of a conversion vessel 25,;which. h'ead section is terminated by plate 36 extending horizontally acrossv saidhead section, Depending.f rom the V 7 plate 38 are the open end pipes 35 which-ex:

tend down to the converter reaction zone. With in the head section-is maintainedan accumulation of particle form contact materiallffi from which contactmaterial flows through pipes 35 to the reaction zone (not shown Connected to the top, of the head section. is the pipe 2 with valve 28. therein. Connected between the; hop-.

per 20 and converter head section 2A'isthe pipe 22 whichshould be of suchlength that the head created by the column of contact material there in maybe greater than the pressure differential between the convertor head section2 4 and hopper 26. i This contact material feed pipe 22. maybe of any desiredcross sectional shape, but thejcross. v sectional area thereof must be sufiicientto allow..,

thedesired contact material. flow rates. It is obvious that two or moresrnaller pipes. could be used instead of one single'pipe." lvlo'r e'over,these pipes'i need not be' absolutely vertical but may formlany slope with the'hori'zontalthat is g'reater than the normal angle of reposeofthe;

tact material. being used. Verticalpipes howa ever, have been'found prefer-able;

In the description and claiming of this invention, theterm contact material feedpipe will be used in a sense sum ciently broad to cove the use of one or more pipes having a ny, slope with. the horizontal which is greater than the. norf-f'.

mal angle of repose or thefcontact materialfand 1 having any desired'cross sectional'shap'el' n the} description and 'in' the. claimingfof this' inven.

tion the. term head as used in connection with".

the column or contact 'rnaterial in thegr eeq leg) to the conversion zone or to the. conversion zone.

l' am er is ni nd 'j mea t i iellys eht of se wstm te e iet ei 'i e lqqmm s q sj its lower .e dpe u i Q f l cr ss-se ti n l.

a- Th h ad m y bev de rmin d by m asure, in -il'lq-yfllli o th medicsea ovei slg sr.

unit of volumeof the contact material measured as a substantially compact mass of downwardly flowing particles and dividing by the cross-sectionar area of the feed leg at its lower end.

Connected to pipe 22 at location adjacent to the connection 31 between the hopper 29 and pipe 22 are downwardly sloping pipes 33 and 3! in which are the valves 34 and 32 respectively. Connected to the hopper 20 at a location adjacent to the connection between hopper 20 and pipe 22 is the downwardl sloping pipe 29 with valve 30 therein. The slope of any of these pipes with the horizontal is at least equal to the angle of slide of the contact material used. This angle of slide is that minimum angle of a flat smooth surface with the horizontal required for gravitational slide therefor of a layer of contact material one particle thick.

In operation particle formcontact mass material is delivered by a conveyor to pipe 2| through which it passes to the accumulation of contact material 38 in hopper 20, From the bottom of the hopper 20 contact material continuously flows through verticalpipe 22 to the head section 24 of the convertor and then through pipes'35 to the conversion zone. The contact material flow from the bottom of the conversion zone is throttled so asto maintain the contact material in the conversion zone and in the pipe 22 asa substantially continuous column or stream of closely packed particle form downwardly flowing contact mass material. The pressure in the conversion zone may be above atmospheric, for example, in the order of eight pounds per square inch gauge. Inert gas, such as steam, is introduced through control valve 28 and pipe 21 into the head section 24 in the space above the accumulation of contact material 26 therein at such a rate as to maintain the pressure in head section 24 equal to or slightly above that in the convertor. Thus conversion vapors are prevented from entering head section 24 and flowing upwards through pipe 22, but a limited amount of inert gas does fiow upwards through the column of contact material in pipe 22 and out through vent 23 near'the top of hopper 20. If the percentage of undersized contact material, say, for example, 300 mesh size material, present in the supply to pipe 22 is greater than the maximum percentage of such material which will be swept down through pipe 22 to the convertor by the normal size material particles, say for example, 10-30 mesh size, then the excess of said undersized material will accumulate in that section of the pipe 22 adjacent its connection with the hopper 20. Such accumulated undersized contact material and some normal size material is peritions involved. As an example, it was found that in: an, apparatus having a 20 foot vertical feed p pe connected at its lower end to a chamber wherein air pressure was 5 to 6 pounds per square inch gauge and at its upper end to a supply funnel at 0 pounds per square inch gauge, when the linear rate of flow of a nominal 8 to 30 mesh particle form contact mass material of approximate- 1y 48 pounds per cubic foot apparent unpacked density wasabout 2 to 20 feet per minute, the;

undersized contact material was found to accumulate inthe pipe within about the upper third and principally at the inlet to said pipe. I

Sincethe principal accumulation of undersized contact material particles occurs generally at or near the upper end of the feed pipe, material withdrawn from only that location may contain lower percentage of the normal size particles of contact material, it is generall preferableto withdraw material only fromthat location. An

apparatus more suitable for accomplishing this purpose is shown in Figure 2.

In Figure 2, is shown a hopper 20 and the upper section of a contact material feed pipe 22, the lower end of which pipe connects into a convertor head section (not shown) in which is maintained a gaseous pressure, The upper end of pipe 22 is closed by plate 39 to which is connected and through which extends the pipe 40, the upper end of which is connected to the bottom of the hopper 20. The pipe 4!! may extend a short distance, for example, about one or two ieetor less, down within pipe 22 thereby providing the vapor-solid disengaging space Si in the top section of pipe 22. Connected to the pipe 22 near the top of space 5| is the vent pipe 43. v The inert blanket gas from the converter head section passes up through the column of contact,

material maintained in pipe 22 and disengages from the contact material in the lower section of the space 5| and passes from the system through pipe 43. If desired the cover plate 39 may be omitted and vapor withdrawn at this location. Excess undersized contact material particles, if present accumulate mainly at the surface 4| .of the contact column and may be easily withdrawn through pipe 42 and control valve 50 therein before the accumulation of said material becomes sufficient to cause interference with the flow of contact material in pipe 22, 7 It is important that the slope of pipe 42 be sufiicient to permit fiow of contact material therethrough. slopesof 40 or more with the horizontal have been found sat.- isfactory for most particle form contact materials. i It should be understood that the hopper 20 1 Figures 1 and 2 neednot necessarily be a separate vessel but may be merely an enlarged connecting pipe between a conveyor and the top of the contact material feed pipe. Unless otherwise specified, the word hopper as used in this specification, and in the claiming of this invention will be used in a sense sufficiently broad to cover either construction. I Q

In Figure 3 is shown an example of this latter construction' In this figure, 45is the contact material'passage pipe from a contact material conveyor (not shown) and 46 isa vertical continuation thereof. Positioned concentrically with pipe 16 is pipe 41 which is connected to pipe 46 and closed off at its upper end by plate 52. The

vapor and contact material flow rates and other variables inherent in a given specific application. The proper location of these pipes is best determined experimentally for. the particularcondilower end of pipe 41 is connected to pipe 22 by means of the conical section 53. The lower end this. conical section. H

7. -I In operation inert-g-asaiter passingzi upwards through-convertor feedpipe 'n countercnrrent to contact material -'flow therein disengages from the contact material at srirface'AS aruideaves the system through vent pipe 43. Ifthe ressure-at the top of -the-pipe 22 is-to-be maintained other than. atmospheric, the valve -11 in pipe is used to throttle the 'gas" flow therethrough. 1 Excessunder'sized contact mate-rial, ifpresent-accumulates at the'surface 48 and a short distance there- A-m'eth'od of Withdrawing a side stream of contact materialfrom'the convertor contact materialfeed system 'which consists almost entirely of undersized contactmaterial particles is shown-in Figures 4 and 5. Figure i is an elevational view; parti ally in section, showing theu-pper-end of-a convertor feed pipe-22, a hopper=20- andinserted therebetweenan apparatus fcrremov'al of'u'ndersized-contact= material. Figure 5 which should: be=read-,together with Figure 4. is asectional view of thisapparatus taken atline 5+5of-Figure 4. A' pipe 40 is-connected to-thetop-51oftherectangular-boir-shaped vessel-56 and extends a short distance-downinto the vessel. The lower end of vessei'56 isclosed'partially-by plate "wand partially'by' the pairs of oppositely placed plates'BB a-ndffifi which-slpe-downwards from the sides of vessel'56 to-the periphery of-the pipe 22"t0"'Which they are-fitted'and welded at a location somewhat belowthe upper end, of said'pipe22. Thusth'er'ekis formed a-tapered'drain section on the bottom ofvessel 56, near-the bottom of which drainsection-is connected a drain'pip'e 42 with valve '50 therein; Nearthe upper end'of the pipe 22 is fitted and welded a' fun-nelofrectangular,

cross sectionalshapewhich is formed bypairs of oppositely placed plates 62 and 62 the plates 2 62 sloping upwards from pipe 22- to twooppQosite side's of the vesse'l i and attached thereto' and the plates Bl sloping upwards from pipe 22 so'as' to; form the. bottom baffles of-;the two bailie formed walls to beidescribed hereinafter. The ves'sel '5fi is internally divided'into a'vapor inlet section .12, a" contact material-passageway 13'and a vapor; outlet" section 14 'by means of two vertical wall's'formed byftwo. rows of'superp'osed plate bafiles 59 extending horizontally across the vessel 56' in a direction perpendicular" to'that of, the drawing. These plates are so spaced and'arranged as to form essentiallytwo parallellouvered or slotted'walls through the slots of which vapors may freely pass but. through which the'contact material will not fall or flow. It'will'be seen that the topjplate'baffles of each wall. extend up to and are connected tosthe top 57" of vessel "5Bthereby preventing vapor channeling. over. the top of the. contact'material column confined between thetwo Also to prevent bypassing of around that portion of conduit 22" extending thereinto;i'vertical-iplate:bafiles H :are connected betweenethe :upperziendiof pipexf22 and the plates GZuimthesvessel drain section; Connected to op-v positezsideszof the vesselnSBare vapor inlet pipe 54 withvalVeaSFrtherein-and 'vaporv outlet pipe 80.

1 In operation; contact material is 1 directed into the -;passag-e-wayl 'ISyby pipe 40 and then-vfiows downwards stherethrough as a substantially continuous lcolumn of closely packed aparticle;.-form contact: mass; 1 material. 'The contact material then passes' intoapipez Eur-through the funnel formed.sbyyplatestfil and ..-.62: and finally passes down. through rpipe 22 to :the convertor (not shown); which .is-operatingmnder a gaseous pressure. It: can be=seen that.v the. column .of .contact material zinwpassagewayJ'l 3; is essentially. an unbroken: continuation of the column ofocontact material inipipe 22. Inert vapors ironrtheconvertor after passing upwards through 13118;.001- umnof contact material in pipe 22jpassesthrough the :column of contact -.material =in2.column .13

or: through part 1 of asaid-ycolumn and. disengages zontally' across the :column of contactmaterial in passageway 13 and I also disengage therefrom at said disengagingsurfaces. :The combined velocity-10f these-.twogvapor; streams? in-the slotted spaces between bafiles '59g: adjacent; the ,vapor outlet section-l4 is thus maintained sufficient to result in -the entrainment of; the undersized, contact; material aparticles;into. the sectioni'l b but insufiicient. to; so. entrain :the normal size .par-

ticles. The crosssectional area of thesection-M.

being considerably.greatenthanthat of: the slot spaces- 15 between baffles=59 the .vaPOr velocity in. said..section-=1 4a falls; .belowthat required to entrain' thegundersized contact material and: said contact material'fallsto the drain section 16- of vessel 56 frorn-=which it is withdrawn. through pipe 42; and control :valve 50 therein. The 1eflluing the normal sizema-teria-l .willvary-dependent upon the inherentvari-ables in any given applicationsuchas size; shape and density of contact material gparticles, thecnature of the vapor and the temperaturenand pressure of the operation.

.. Thus the required rate must be experimentally determined for each; application but with: proper apparatus design; considerable flexibility; of .vapor rate is obtaina-ble-.- merely by 1 regulation of vapor rate charged through pipe: 54. Experimental work has. shown that for an ordinary granular clay typecatalyst. of an apparent. unpackeddensityofabout 37 'pounds per cubic foot, the 1 linear .velocity; of, atmosphericv pressure air at-BO" Enrequiredto entrain particles of -0-.10 inch and- 0.02 inch -diameter -was about-30 :feet, per second and 6 feet persecond respectively.

.Ashas been hereinbefore stated acertain maximumpercentage of undersized contact material particles. .may beyswept. down through the convertorieedpipe. into the convertor by the..normal size particles without interruptions in the conmum limiting percentage, although more may -i through the feed pipe and the nature of the vapor and the rate of flow thereof in the feed pipe, it is obvious that no single limiting percentage figure may be given for the operation of this invention and that the limiting percentage value must be determined for each specific application. With the aid of disclosures given in this specification those skilled in the art may readily make such determinations. As an example of the determination of this value for a specific application, it was found that when a particle form.

contact material having an apparent unpacked density of 48 pounds per cubic foot and an average particle size of about 0.027 inch diameter was passed downwards at a linear velocity of about 22 feet per minute through a vertical pipe having a length of 20 feet and terminating in a chamber wherein an air pressure of pounds per square inch gauge and temperature of 70 F. is maintained over an accumulation of contact material, the maximum percentage of:

undersized contact material particles of diameter less than about 016 inch which may be swept down through said pipe without interruption of the flow of contact material insaid pipe is in the order of 5 to 10 per cent by weight of the total contact material flow.

It should be understood that the various embodiments of this invention and examples of its operation and application given herein are intended to be merely exemplary in character and are not intended in any way to limit the scope of this invention except insofar as such limitations are specified in the appended claims.

I claim:

1. In a process of the type described the method of introducing particle form contact mass material to a convertor against a gaseous pressure therein, comprising: continuously supplying said contact material to said convertor from an elongated confined substantially compact stream of particle form contact material extending upwards from said convertor and having a greater head of contact material than the pressure in said convertor; continuously supplying particle form contact mass material to the upper end of said confined substantially compact stream of contact ment of normal size contact material in the dismaterial; permitting the flow up through said per supply end thereof; passing additional gas transversely across said longitudinal section of said stream and disengaging said gas from surfaces along the opposite side of said longitudinal section of said stream along with said gas from said convertor; substantially preventing entrainengaging gas from said longitudinal section of said column by control of rate of flow of said additional transversely flowing gas, but permitting the entrainment in said disengaging gas of at least that quantity of undersized contact mass material particles which is in excess of the quantity of such material which may be swept by normal size contact material particles down in said stream of contact material into said convertor without interruption of the flow of said contact material in said column; and withdrawing said I disengaged vapors and entrained undersized contact material from the system.

. 2. In a process of the type described the method of introducing particle form contact mass material to a convertor against a gaseous pressure therein, comprising: continuously supplying said contact material to said convertor from an elongated confined substantially compact column of particle form contact material extending upwards from said convertor and having a greater. head of contact material than the pressure insaid convertor; continuously supplying particle form contact material to a continuation section of the upper end of said confined column of contact material, said continuation section of said column being confined on two sides by impervious solid walls and on two oppositely opposed sides by foraminate walls pervious to the flow of gas therethrough but impervious to the normal gravitational flow of contact material particles therethrough; permitting the flow up through said confined column of contact material of the limited quantitiesof' gas induced therethrough by the pressure'in said convertor and withdrawing said gas from the specially confined continuation of said column through one of said foraminate confining walls; passing controlled quantities of additional gas through the other of said foraminate confining walls, transversely across the confined continuation of said contact material column and withdrawing said additional gas through the opposite foraminate wall along with said gas from said convertor, said gas being withdrawn without the entrainment therein of any substantial amount of normal sized contact mass material particles but with the entrainment of at least that quantity of undersized contact material particles in excess of the quantity of such material which may be swept by normal size contact material particles down in said column of contact material into said convertor without interruption of the flow of said contact material in said column;

and withdrawing said efliuent vapors and entrained undersize contact material from the systom.

3. In an apparatus of the type described an apparatus for continuously introducing particle form contact mass material against a gaseous pressure in a contacting vessel wherein gases are contacted with a continuously flowing substantially compact mass of particle form contact mass material, comprising an elongated contact material feed pipe connected to said contacting vessel and extending upwards therefrom, said feed pipe being of suificient height that the head of the substantially compact column of particle form contact mass material maintained therein will be greater than the pressure in said contacting vessel; a supply hopper located above the upper extremity of said feed pipe; two oppositely opposed upwardly extending foraminate walls, pervious to flow of vapor therethrough and imperyious to the gravitational flow of particle form ufnntio'r'id elevational-l -abetween isaid s'upply hopper an d saidfedpipe"thereby 'forinifig a' contact :m-a-

11 contact material therethroug'h' when-the Contact materiatflat is as a substantially 'compaot'fcolsaid w allls =b eing r-sp'a'cea apart and positri al passageway th'ere' between impervious means defining the' remaining wv'allsof Saiagqaas- Y inearis fdr continuous1y"'upp1ying par o said supply hoprenting-flow of *eontaet material -irom said passageway to said feedfipipe rmeans to enclosesaid foraminat'e wans, thereby? forming gas" inlet chamber orr-"one side thereof and a *gas' outlet chamberon-the 'op'posite=side-thereof means to introduce gas at a controlled rate into said inlet chamber-qmeans-to -"wi-thdraiw 'ga's-- from said outlet 'chamber an'd means to "withdraw undersized; contact matria-l "particles fromsaid= outlet chamber.

4. In an-apparatus of the typedescribed'wherein a particle form eonta'ct mass *material-is continnously rintroduced' against a "gaseous pressure into *a contacting lvessel wherein gases are" contacted with a continuously-flowing substantially compact mass bfpar-ticle-form contact massmaterial; combination: a' contacting vessel, an

elongatedcontact inateria-l feed -pipe= connected to said "contactmg vessel and" extending upwards therefrom; said feed pipe being of su-flioient height that the 'l1ead of the substantially vcompact coluinn of particle for-m 'contact mass material-niaintaiiied tlierein will be greater" than the pressure in said "ontacting vessel; a supply hopper located above tl'ie upper extremity 'of saidrfe i e at close-d vessercorinected between said hopper and said reed-wipertwo 'upwaruly :extendmg oppo- 7 A nobst cte'd, vertical- 'passag fo'r' gravitynow "of contaet' material from said hoppe" to" saiii pajssafgewayg means for *disitely' opposedioraminate walls, pervious to flow 1 of vapors therethroughand impervious to gravitational flow of contactmaterial particles therethrouglr-whenthe downward flow of -contact material'between said Walls is-as a substantially compact-column; said Walls being spaced apart and positioned-within said vessel andextending from wall to wall 'of said' vessel in one direction so as te-divide it into'a gas inlet chamber onone "sideof said walls, a contact material passage-way between said walls and-"a-gas outlet passage on the opposite side of said "Walls; means for continuous' supplynof particle form contact material fromsaid hopper to the upper end of said pas- "sage'way in "said clo'seclves'selg means for directing contact' material fiow'irom' said passageway to said'feed pipe; means to introduce gas at controlled-ratesinto said gas inlet chamber; means to withdraw sai'd gas from saidgas outlet'cham- -ber; means to 'withdra'wcontrolled quantities of undersized contact material 'from said outlet chamber, "means to continuously supply particle formconta'ct' material to said supply hopper, and means to maintain an" inert gaseous pressure in theupperend of *said contacting .vessel above the Number Name Date 890,625 Edison; June 16, 1908 2,290,580 De"gnen et a1 July 21, 1942 2,321,015 Davis June 8, 1943 2,348,156" Sheppard Q May 2, 1944 2,373,3655 Las'siat May 22'; 1945 

